(a) Field of the Invention
The present invention relates to a threading apparatus, and more particularly to a threading apparatus for a lower looper of an overlock sewing machine.
(b) Description of the Prior Art
An overlock sewing machine which is commercially available at present comprises an arm disposed on a base and a needle extending downward from a free end portion of the arm for conducting sewing operations. The overlock sewing machine is provided for forming a hem or a selvage on the edge portions of a piece of cloth and comprises an upper looper and a lower looper pivotally disposed in the base thereof and operatable in a reciprocating or oscillating action. The upper looper and the lower lopper are engageable with each other. Each of the upper looper and the lower lopper carries a thread, and the threads can be engaged with each other during sewing operations.
A conventional lower looper is shown in FIG. 8 and comprises a bar 90 having a lower end pivotally supported in the base of the sewing machine by an ankle 91, a catch 92 fixed on an upper end of the bar 90, and a guide 97 fixed on the middle portion of the bar 90. A hole 98 is formed in the guide 97. The catch 92 includes a straight arm 93 formed on the upper end of the catch 92 and substantially perpendicular to the bar 90. A slot 94 is formed in one side of the arm 93. An orifice 95 is formed in the front end of the arm 93 and is communicated with the slot 94. A conduit 96 is formed in the rear end of the arm 93 and is communicated with the slot 94. A thread 99 passes through the hole 98 of the guide 97 and is threaded into the conduit 96, and then passes through the orifice 95 so that the portion of the thread 99 located between the orifice 95 and the channel 96 can be received in the slot 94 and so that this portion of the thread 99 will not be interfered during sewing operations.
However, in order to be operated precisely and accurately, the arm 93 is preferably made as thin as possible so that the size of the conduit 96 should be very small. This causes difficulty for threading the thread 99 through the conduit 96 of the arm 93.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional overlock sewing machine.